The signs on every playground in my city, New York, say this: "Playground rules prohibit adults except in the company of children."

Apparently, because any adult who simply wants to sit on a bench and watch kids at play could be a creep, it's best to just ban them all. The idea that children and adults go naturally together has been replaced by distrust and disgust.

There was a case here about three years ago when seven chess players playing outside were fined for ... wait for it ... playing chess. Their chess tables — concrete ones, placed there by the city — were deemed too close to the kids, so the men were booted.

It didn't matter that they hadn't caused any trouble. In fact, the grizzled guys had taken it upon themselves to teach some of the local kids how to play the game of kings.

The reality of the situation — the men's kindness — didn't matter. All that mattered were the fantasies conjured up by "what if" thinking: What if they turned out to be monsters?

By separating the generations this way, we are creating a new society, one that actively distrusts anyone who wants to help a kid other than his own. Compare this anxiety with what goes on in Japan. There the youngest kids wear bright yellow hats when they go to school.

"Doesn't that put them in danger?" asked a friend I was telling about this. To her, a kid who calls attention to himself is a kid who could be attracting a predator.

But attracting adult attention is exactly what the yellow hats are supposed to do. In Japan, the assumption is that the easier it is to see children the easier it is for grown-ups to look out for them.

Japan's belief is that children are our collective responsibility. America's is that children are private treasures under constant threat of theft.

Which brings me to the flip side of our obsession with stranger danger: the idea that anytime a parent lets her kids do anything on their own, she is actually requiring the rest of us grown-ups to "baby-sit" them free of charge.

This topic came up recently when a story from Canada went viral. An 11-year-old boy in an Alberta mall was detained by the staff of the Lego store because he was shopping there without a parent.

It didn't matter that he was perfectly well-behaved, only that when a store employee asked his age, he was deemed an unbearable burden to the store. The manager had him detained until his father could come pick him up.

This detention outraged many people, but a significant contingent sided with the store, saying that the employees there shouldn't have had to "baby-sit" the boy.

But, but — no one did have to baby-sit him. He was just a person in public, albeit a young one.

If some problem had come up — say he poked himself in the eye with a tiny Lego sword — well, then, yes, some adult might have had to come to his aid. But that is not baby-sitting! That is one human being's helping another who happens to be 11 years old.

Most kids making their way to school or playing in the park are not going to need major assistance from anyone, adult or otherwise. But if they do, I'd like to think most of us would give it ungrudgingly.

Old and young have always interacted. Adults who enjoy being around kids are, for the most part, just that. Not predators.

And kids who are out and about in the world are just that. Not a big unpaid job for the rest of us.

I'm not sure about the yellow hats, but Japan has the right idea. Looking out for everyone beats trusting no one.